Brake warning light

[MichaelSB]

Can anyone suggest why my brake warning light keeps lighting up randomly, I have no other symptoms and when I asked the main dealer they just said no fault found.

I think I heard it suggested that this warning light has a dual function but I do not know what the other function is.

Any ideas please.

PS It is NOT the Handbrake light.

[almcl]

From my '93's handbook:

"When the warning light is illuminated, it indicates that the brake fluid level has fallen below a pre-determined level.

When the warning light is illuminated in conjunction with the anti-lock failure warning light it warns of very low brake fluid level or low boost pressure."

From the service manual:

"The brake warning is illuminated because an earth connection for the waning lamp is made via switch contacts located in the reservoir.

There's more, but you really need to read the manual.

[MichaelSB]

Hi Al

Thank you for the info.

The brake warning light is the only one that is coming on and the car has no symptom's or low brake fluid so I wonder if I have a dodgy switch in the brake reservoir.

Michael

[almcl]

Might be worth disconnecting both plugs on the fluid reservoir and cleaning them then reconnecting?

If it persists after that then it might be a pressure issue, which is the other function of the light, although this should trip the ABS light also..

[MichaelSB]

Hi Al

I did think about disconnecting the electrics from the reservoir, I had a look today and on top of the connection is a wire clip, do you know if it only holds the electrical connection or is there a risk of fluid leaking from it if I remove it?

Thanks

[almcl]

It's only electrics *BUT* the grommet or other sealing fixture is 13 years old so a leak is always a possibility, especially if it has to be 'persuaded' to disconnect.

[paulhutton]

I have exactly the same problem on my '96 Celebration, and had exactly the same reaction from Stratstones at the last service!

I have had the plug out, cleaned and replaced it with no improvement. I have checked the wiring diagrams but can see no function, other than low brake fluid for this warning light.

Someone out there must have an answer!!!

Paul H

[Linxman]

And I'm another one, wth my '95 4.0! Surely this must be a fairly well known fault?

Phil B

[MichaelSB]

I think the man/woman with the answer is playing hard to get.

Come on now tell us what you know

[poprivet]

I'll throw a couple of thoughts in based on the Teeves system, your later models may not be the same though.

1. Accumulator ball needs charging. Braking can reduce the system pressure below the threshold needed, I believe this will light the warning lamp.

2. Check the fluid levels in both front and rear sections of the reservoir with ignition on and the accumulator pump up to full pressure and stopped. The system will empty to the volume of the accumulator ball following a long rest. It is normal for the fluid level to be well above MAX if the system is unpressurised.

3. Partially flooded float

4. Poor/corroded/heat stressed wiring or connectors.

5. System fully bled and fluid within age limit.

Pop

[almcl]

It could, of course, be a failing pump or an intermittent combined pressure switch.

The light is earthed either via the brake pressure switch, or via the level switch in the reservoir, according to the circuit digram.

If the level switch is blameless (and you are sure the accumulator was fully charged when you checked the level) then the pressure switch is a known failure point.